1. Field of the Invention
The present invention relates to wheeled carriages of the type wherein the wheels are in the form of casters. The invention relates in particular to means for locking the casters so as to prevent rotation of the caster wheels and to prevent swiveling motion in the case of swivel casters.
2. Description of the Prior Art
In caster-wheeled carriages, it is frequently desirable to lock the caster wheels against rotation for holding the carriage in a predetermined location and preventing any accidental movement thereof. It is well known to provide a separate caster brake or lock for each caster wheel. Such brake or lock assemblies are disclosed, for example in U.S. Pat. No. 3,942,608. It is also known to provide locking mechanisms which simultaneously lock more than one caster.
This latter type of caster locking mechanism is disclosed, for example, in U.S. Pat. Nos. 3,304,116 and 4,164,355. This type of assembly provides a locking ring overlying each of several swivel caster wheels substantially coaxially with the caster swivel axis. The locking rings are all interconnected by a locking frame which is moved by means of a cam mechanism between an upper release position wherein the rings are out of contact with the caster wheels to permit free movement thereof and a lowered locking position wherein the rings firmly engage the caster wheels to prevent rotation thereof and also to prevent swiveling thereof. In that prior art device the locking assembly is actuated by a handle member which rotates an eccentric cam through an angle of about 90.degree. between the release and locking configurations. That arrangement is satisfactory where there is a large amount of under-chassis clearance, such as hospital beds or the like, to accommodate the wide-angle rotation, or where the handle assembly can extend beyond the ends of the chassis.
But that prior arrangement is not suitable for use where there is very limited clearance which will not permit a full 90.degree. rotation of the cam member. For example, in carriages with low-slung chassis, such as garage mechanic tool chests, there are only a few inches of clearance between the chassis and the floor. This would make it effectively impossible for a user to exert sufficient leverage to rotate a cam mechanism through a 90.degree. angle. It would be possible to extend a cam shaft beyond an end of the carriage, but this increases the effective floor space occupied by the carriage and also necessitates that the carriage always be utilized in an orientation which maintains access to the end from which the actuator shaft projects.